Vacuum tube



A 1933- R. G. RICHARDSON 1,932,637

VACUUM TUBE L A Filed June 18, 1928 f Inuan ur' RndnayEEicZ-LardsunPatented Oct. 31, 1933 VACUUM TUBE Rodney G. Richardson, Chicago, 111.,assignor, by mesne assignments, to Associated Electric Laboratories,Inc., Chicago, 111., a corporation of Delaware Application June 18,1928. Serial No. 286,105

5 Claims.

This invention relates in general to vacuum tubes; and the object of theinvention is to devise new and improved types of tubes, together withapparatus such as telephone repeaters and the like in which tubes of theimproved form shown herein may be used.

The invention is illustrated by the accompanying drawing in which Fig. 1shows a telephone repeater, Fig. 2 shows a frequency changer, while Fig.3 shows a modified form of segmented tar get for use in the frequencychanger shown in Fig. 2.

Referring to Fig. 1, the reference character 5 indicates what iscommonly known in the art as a cathode ray oscillograph tube. This tubemay correspond generally to the well-known form of cathode rayoscillograph tube manufactured by the Western Electric Company. Itcomprises an evacuated vessel, preferably of glass, in which is mounteda filament or cathode 6, a perforated shield 7, and a tubular anode 8.In addition, the tube contains a target comprising the insulated plates9 and 10, which are disposed at the right-hand end of the tube, asindicated. The cathode 6 is connected in circuit with a battery A bymeans of which it is heated in the well-known manner. The shield '7 ispreferably connected to the cathode as shown, while the anode 8 isconnected to the cathode in series with a battery B.

The reference character 11 indicates a magnetic structure of soft iron,which may be of any desired form, although, as shown in the drawing, thetwo opposite poles should be disposed one on each side of the tube andsubstantially in the plane of the cathode ray beam. Separate magnets maybe used, if desired. The input circuit including the conductors 1 and 2is connected to coils wound on the magnet poles. The two plates 9 and 10are connected to the output circuit comprising conductors 3 and 4 bymeans of an induction coil having the windings 15 and 16. The middlepoint of the winding 15 is connected in series with a battery B to thebattery B.

In the operation of the repeater, the cathode 6 is heated by the batteryA and emits electrons, part of which are drawn through the opening inthe shield '7 and through the opening in the anode 8 by the voltageimpressed on the anode 8 by the battery B, aided by the voltageimpressed on the plates 9 and 10 by the batteries B and B in series. Inthis manner, a so-called cathode ray or beam is produced which impingeson the target comprising plates 9 and 10. The parts may be so disposedin the tube that the beam will normally strike the target at a pointsomewhat removed from the center thereof. The beam can then be broughtto the center of the target by adjusting the rheostat 13, which variesthe amount of current flowing through the coil 12. The field produced bythe coil 12 will displace the beam more or less so that it can beaccurately positioned on the target. It may be stated also that the coil12 maintains the flux substantially at the point where the maximumchange in flux will take place responsive to a given current change inthe input circuit, and thus renders the device more sensitive toincoming currents.

It may be explaned at this point that although the various partscorrespond generally to the corresponding parts of the well-knowncathode ray oscillograph, they are somewhat modified in order to adaptthe tube to use as a telephone repeater. The opening in the shield '7and likewise the opening in the anode 8 should be much larger than isordinarily used, so as to produce a beam of considerable thickness. Itis also desirable to have the tube comparatively short, with the targetdisposed relatively close to the anode 8. With these modifications, acathode beam having a fairly high current value can be obtained. Thevoltage of batteries B and B should be as low as possible, as thesensitivity of the beam to a deflecting field is inversely proportionalto its velocity.

In the operation of the device as a telephone repeater, the incomingvoice currents over the circuit including conductors 1 and 2 produceflux changes in the electromagnet 11, which bend the beam back and forthand change the point at which it contacts the target. Thus, at a giveninstant the major portion of the beam may impinge on the plate 9, whileat another instant, due to bending of the beam, it may impinge more onthe plate 10. It will be seen that this movement of the beam willproduce current changes in the two halves of the induction coil winding15, which is included in the return path of the beam through batteries Band B, whereby corresponding fluctuations are induced in the secondarywinding 16 of the induction coil which is connected in the outputcircuit.

Referring now to the frequency changer shown in Fig. 2, the referencecharacter 35 indicates a cathode ray oscillograph tube which is similarto the tube shown in Fig. 1. The target is dififerent, however, and alsodifierent means is employed for bending the cathode ray or beam.

The target is circular in form, as indicated in the drawing, andcomprises a number of insulated segments, the number used depending onthe desired ratio between the generator frequency available and thefrequency which it is desired to produce. The odd-numbered segments suchas 51, 53, etc., are all connected together and a common lead extends tothe primary winding of the transformer T, from which a return path maybe traced through the two batteries to the cathode. The evennumberedsegments of the target, such as 52, 54, etc., are also connectedtogether and a common lead is extended to the switch S by means of whichthe common lead can be connected to the return path through the battery.

The means for causing the cathode beam to trace a circular path so as tofollow the target comprises two pairs of plates, 41 and 42, and 43 and44, together with a generator for charging the plates electrostatically.The generator is indicated by the reference character G and may be anysource of alternating current which is to be used as the basic sourcewhose frequency is to be multiplied. Two resistances, 47 and 48, areconnected across the terminals of the generator G, resistance 48 havingin series with it an inductance 46, while the resistance 47 has inseries with it a capacity 45. The plates 41 and 42 are connected acrossthe terminals of the resistance 48, while the plates 43 and 44 areconnected across the terminals of the resistance 47. The circuitarrangement shown produces impressed voltages on the two pairs of plateswhich are out of phase and by suitable adjustment the cathode beam,which is bent by the electrostatic charges on the plates, may be causedto trace a circular path, so as to contact successively with thedifferent segments of the target.

As in the case of the device shown in Fig. 1, it is desirable that theparts be so arranged as to produce a cathode beam of considerablethickness. This beam preferably should be large enough to substantiallycover one segment of the target in order to produce a fairly good waveform in the output circuit. It may be desirable also in this connectionto connect a filter such as is indicated at F in shunt of the primarywinding of the transformer T.

The operation of the device will be readily understood in view of theforegoing. The cathode beam is included in a circuit which at a giveninstant includes a live segment of the target, the primary winding ofthe transformer T, and the two batteries in series. The current in thiscircuit will rise to a maximum as the beam becomes centered on the livesegment of the target and will decrease to zero when the beam passes onto the adjacent dead segment, rising again to a maximum as the beamreaches the next live segment, etc. The rise and fall of current in theprimary winding of the transformer T, of course, induces currents in thesecondary winding which may be used for any desired purpose. Thefrequency of the secondary current generated depends on the number ofsegments in. the target and this, of course, is determined in advance soas to produce the desired frequency. Amplifiers may be used beyond thetransformer T in the well-known manner in case large amounts of currenthave to be supplied.

The modified form of target shown in Fig. 3

is similar to the target shown in Fig. 2 except that it has two rows ofsegments 61 and 62 instead of only one row. The object of themodification is to make two difierent frequencies available. There aremore segments in one row 61 than there are in row 62, and the beam ismade to traverse one row or the other depending on the frequencydesired. Control of the beam is effected by any suitable means whichwill produce changes in the amplitude of the movement of the beam. Thiscan be done conveniently, for example, by adjusting the field of thegenerator G so as to vary the voltage supplied to the electrostaticplates.

It will be understood that the devices shown herein are illustrativeonly and that modifications and adaptations can be made withoutdeparting from the spirit of the invention. I do not, therefore, wish tobe limited to the precise forms of the invention which are shown anddescribed herein, but desire to include and have protected by LettersPatent all forms of my invention which come within the scope of theappended claims.

What is claimed is: k

1. In a cathode ray device, means for producing a beam of electrons, acircuit including said beam and having two parallel branches, means foradjusting the beam so that a definite amount thereof is included in eachof said branches, and means for deflecting the beam to vary the amountof the beam which is included in said branches, respectively.

2. In a telephone repeater, means for producing a beam of electrons, atarget, and means including a source of current and circuit therefor foradjusting the normal position of the beam on the target.

3. In a telephone repeater, a filament for producing a beam ofelectrons, a target comprising two segments in the path of said beam, aninduction coil having the opposite ends of its primary winding connectedto said segments, respectively, a battery connected between the saidfilament and the middle point of said primary winding, and meansincluding a circuit carrying voice currents for modifying the amount ofthe beam which is intercepted by each of said segments to producecorresponding voice currents in the secondary winding of said coil.

4. In a telephone repeater, an electron emitting element, two returnpaths both conducting electrons back to said element simultaneously,means including an input circuit carrying voice currents for producingavibratory motion of the electron stream to vary the amount thereof whichis intercepted by each of said paths, and an output circuit in which thevarying currents in said return paths cooperate to induce voice currentscorresponding to the voice currents in said input circuit.

5. In a telephone repeater, means for producing a beam of electrons, atarget comprising two segments each intercepting a portion of said beam,an output circuit, an input circuit carrying voice currents forproducing deflections of said beam thereby shifting its contact with thetarget so that varying amounts of said beam are intercepted by each ofsaid segments while the beam is maintained in contact with bothsegments, and a local return circuit for said electrons including bothsaid segments and inductively coupled to said output circuit to induceamplified voice currents therein.

RODNEY G. RICHARDSON.

